Scalable metal oxide functionalized GaN nanowire for precise SO2 detection

In this work, GaN nanowires have been formed on Si substrate using production standard stepper lithography and top-down approach. Three different functionalized devices were prepared by the deposition of metal oxidesZnO, WO3 and SnO2 by optimized RF sputtering on nanowires followed by rapid thermal annealing. The elemental composition, crystallinity and surface topography of metal-oxide/GaN nanowires were fully characterized by EDS, XRD, AFM and SEM. The SO2 gas sensing data was collected and analyzed for all three sensors. The ZnO/GaN sensor was found to be the best candidate for precise SO2 detection. To examine the real-world applicability of ZnO/GaN sensor device, its additional sensing properties, including gas sensing adsorption and desorption rate, cross-sensitivity to interfering gases, and long-term stability at various environmental conditions were investigated. Furthermore, principal component analysis has been performed to address the cross-sensitive behavior of ZnO. The SO2 sensing mechanism on metal-oxide/GaN under UV irradiation was discussed as well. Results demonstrate that ZnO functionalized GaN nanowire can be employed as a high performance SO2 sensor.